1. Field of the Invention
One embodiment of the present invention relates to an organometallic complex, and a light-emitting element, a display module, a lighting module, a display device, a light-emitting device, an electronic device, and a lighting device each including the organometallic complex. Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, a method for driving any of them, and a method for manufacturing any of them.
2. Description of the Related Art
As next generation lighting devices or display devices, display devices using light-emitting elements (organic EL elements) in which organic compounds or organometallic complexes are used as light-emitting substances have been developed and reported because of their potential for thinness, lightness, high-speed response to input signals, low power consumption, and the like.
In an organic EL element, voltage application between electrodes, between which a light-emitting layer is interposed, causes recombination of electrons and holes injected from the electrodes, which brings a light-emitting substance into an excited state, and the return from the excited state to the ground state is accompanied by light emission. Since the spectrum of light emitted from a light-emitting substance depends on the light-emitting substance, use of different types of light-emitting substances makes it possible to obtain light-emitting elements which exhibit various colors.
Although displays or lighting devices including light-emitting elements can be suitably used for a variety of electronic devices as described above, their performance has plenty of room to improve. Specifically, there have not been many kinds of materials that emit green to blue phosphorescence, and further improvement of their characteristics has been demanded.
Patent Document 1 discloses an iridium complex with a ligand including a phenothiazine skeleton.